AC/DC monitor system

A combined AC/DC monitoring system for a recreational vehicle that simultaneously monitors an AC power supply and a DC power supply and that display pre-selected computed variables, comprising:

• a step-down isolation transformer for electrically isolating the AC power supply from the monitoring system and for providing an isolated, stepped-down AC voltage signal to the monitoring system;
• AC voltage monitor input terminals connected to the isolated AC signal for monitoring the isolated AC voltage signal;
• DC voltage monitor input terminals connected to the DC power supply for monitoring a DC voltage for the DC power supply;
• a DC shunt, said DC shunt having a first terminal connected to a positive;
• non-grounded, terminal of the DC power supply and said DC shunt having a second terminal;
• first and second DC current monitor input terminals respectively connected to the first and to the second terminals of the DC shunt for measuring current from the DC power supply;
• an analog-to-digital converter ADC system having respective input terminals connected to the AC voltage monitor input terminals, the DC voltage monitor input terminals, and the DC current monitor input terminals, wherein the ADC provides respective digital output signals indicative of instantaneous values of the isolated AC signal, the DC voltage, and the DC current;
• a microcontroller having input terminals for receiving respective digital output signals of the ADC, said microcontroller digitally computing various respective computed variables from the respective digital output signals received from the ADC;
• a visual display screen that receives signals representative of the computed variables from the microcontroller and that simultaneously visually displays pre-selected ones of the respective computed variables;
• an audible alarm that is selectively activated when a pre-selected computed variable is in a respective alarm condition that is outside a predetermined limit;
• wherein the microcontroller includes keypress terminals for receiving from user-operated switches respective user control signals for operation of the microcontroller;
• wherein the microcontroller provides user menus that are displayed on the display screen and wherein the microcontroller has keypress terminals for receiving respective user control signals from user-operated switches that are operated by a user in conjunction with the user menus to control operation of the microcontroller, the visual display screen, and the audible alarm;
• and
• wherein the computed variables are selected from a group comprising:
• an AC voltage, an AC current, an AC r.m.s. voltage, an AC frequency, a DC current, a DC voltage, DC ampere hours, and temperature.

A method of simultaneously monitoring an AC power supply and a DC power supply for a mobile unit with a combined AC/DC monitoring system, comprising the steps of:

• electrically isolating the AC power supply with a transformer and providing an isolated AC voltage signal to the combined AC/DC monitoring system;
• coupling the isolated AC signal to AC voltage monitor input terminals for monitoring the isolated AC voltage signal;
• coupling the DC power supply to DC voltage monitor input terminals for monitoring a DC voltage for the DC power supply;
• for measurement of DC current from the DC power supply, connecting a first terminal of a DC shunt to a positive, non-grounded terminal of the DC power supply, connecting the first terminal of the DC shunt to a first DC-current monitor input terminal;
• and connecting a second terminal of the DC shunt to a second DC-current monitor input terminal;
• coupling the AC voltage monitor input terminals, the DC voltage monitor input terminals, and the DC current monitor input terminals to input terminals of an analog-to-digital converter ADC system, and the ADC providing respective digital output signals indicative of instantaneous sampled values of the isolated AC signal, the DC voltage, and the DC current;
• receiving respective digital output signals of the ADC at input terminals of a microcontroller and said microcontroller digitally computing various respective computed variables from respective digital output signals received from the ADC;
• a visual display system receiving signals representative of the computed variables from the microcontroller and simultaneously visually displaying a plurality of pre-selected ones of the respective computed variables;
• selectively activating an alarm system when a pre-selected computed variable is in a respective alarm condition that is outside a predetermined limit;
• the microcontroller providing user menus that are displayed on the visual display system;
• the microcontroller receiving at keypress terminals respective user control signals from user-operated switches that are operated by a user in conjunction with the user menus to control operation of the microcontroller, the visual display system, and the alarm system.